Different Concentrations Of Hydrogen Peroxide Research Articles

Effect of hydrogen peroxide on photoelectric properties of high-transmittance FTO films prepared by spray pyrolysis

The FTO film prepared by spray pyrolysis has low efficiency and most of the precursors are discharged in the form of waste steam. According to the high oxidation property of H2O2, it is attempted to improve the film formation rate by changing the concentration of H2O2. Fluorine-doped SnO2 (FTO) thin films with high transmittance were prepared by spray pyrolysis using monobutyltin trichloride as the tin source and ammonium fluoride as the fluorine source. Different concentrations of hydrogen peroxide (0–0.08 M) are added to the precursor solution. In this paper, we studied the effect of hydrogen peroxide on the structure, surface morphology and photoelectric properties of FTO thin films. The results show that the growth rate of the FTO films increased from 6.04 nm/s to 8.36 nm/s with the increase of H2O2 concentration from 0 to 0.08 M. The optimum preparation process is H2O2 concentration controlled at 0.04 M, and FTO thin films suitable for solar cells are prepared. It has excellent performance parameters; carrier concentration:2.74 ∗ 1021 cm−3; carrier mobility:55.92 cm2 V−1 s−1; photoelectric quality factor:2.66 × 10−3·Ω−1and the average transmittance of visible light: 79.87%. At the same time, increasing H2O2 concentration leads to narrowing of optical band gap. Adding appropriate hydrogen peroxide concentration can improve the film production rate and obtain excellent quality films.

Preparation of self-propelled Cu-Pt micromotors and their application in miRNA monitoring

Self-propelled catalytic micromotors offer considerable promise in terms of many applications. Catalytic micromotors are strongly influenced by the presence and concentration of specific ions and chemicals in the environment, making them useful as sensors and actuators. In this work, copper (Cu)-platinum (Pt) micromotors were fabricated by using the magnetron sputtering method for the first time in the literature and their applications based on the detection of miRNA-21 were evaluated. We analyzed the dependence of the mobility of Cu-Pt micromotors using different concentrations of hydrogen peroxide (H$_{2}$O$_{2})$. The presence of surfactants in the environment is also important for the movement of the micromotors. Thus, we studied the effect of three different surfactants: anionic as sodium dodecyl sulfate (SDS), cationic as cetyltrimethylammonium bromide (CTAB), and nonionic as Triton X-100. Cu-Pt micromotor motion was observed even at very low concentrations of surfactant (0.01%) and hydrogen peroxide (0.25%). miRNAs have been regarded as biomarker candidates in early diagnosis. Our sensing strategy relied on dye-labeled single-stranded DNA immobilization onto Cu-Pt micromotors that recognize the target miRNA-21. The changes in the fluorescence intensity as well as the changes in the speed of micromotors were examined before and after hybridization.

Reactive Oxygen Species Induces Lipid Droplet Accumulation in HepG2 Cells by Increasing Perilipin 2 Expression.

Non-alcoholic fatty liver disease (NAFLD) has become the world’s most common liver disease. The disease can develop liver fibrosis or even carcinomas from the initial hepatic steatosis, and this process is influenced by many factors. Reactive oxygen species (ROS), as potent oxidants in cells, have been reported previously to play an important role in the development of NAFLD progression via promoting neutral lipid accumulation. Here, we found that ROS can promote lipid droplet formation in hepatocytes by promoting perilipin2 (PLIN2) expression. First, we used different concentrations of hydrogen peroxide to treat HepG2 cells and found that the number of lipid droplets in the cells increased, however also that this effect was dose-independent. Then, the mRNA level of several lipid droplet-associated genes was detected with hydrogen peroxide treatment and the expression of PLIN2, PLIN5, and FSP27 genes was significantly up-regulated (p < 0.05). We overexpressed PLIN2 in HepG2 cells and found that the lipid droplets in the cells were markedly increased. Interference with PLIN2 inhibits ROS-induced lipid droplet formation, revealing that PLIN2 is a critical factor in this process. We subsequently analyzed the regulatory pathway and protein interaction network that is involved in PLIN2 and found that PLIN2 can regulate intracellular lipid metabolism through the PPARα/RXRA and CREB/CREBBP signaling pathways. The majority of the data indicated the correlation between hydrogen peroxide-induced PLIN2 and lipid droplet upregulation. In conclusion, ROS up-regulates the expression of PLIN2 in hepatocytes, whereas PLIN2 promotes the formation of lipid droplets resulting in lipid accumulation in liver tissues.

Photocatalytic degradation of reactive black 5 on the surface of tin oxide microrods.

A simple co-precipitation technique is proposed for synthesis of tin oxide (SnO2) microrods. Stannous chloride and urea were used during synthesis. X-ray powder diffraction (XRD) analysis revealed that the annealed product consists of SnO2 microrods having tetragonal unit cells, while scanning electron microscopy (SEM) analysis revealed the rod-like morphology of a synthesized product. These synthesized microrods are used as photocatalyst for the degradation of reactive black 5 (RB5). Degradation kinetics of RB5 are monitored under daylight in different concentrations of hydrogen peroxide (H2O2) and catalyst. The percentage of RB5 conversion is also calculated at various concentrations of hydrogen peroxide and catalyst which demonstrate that RB5 shows high catalytic degradation at high concentrations of hydrogen peroxide and catalyst.

Effect of oxidative stress on vital indicators of Acanthamoeba castellanii (T4 genotype).

Acanthamoeba has 22 genotypes with the T4 genotype being the main causative agent of amoebic granulomatous encephalitis and keratitis. Because the molecular mechanisms of the immune defenses of neutrophils and macrophages against histoparasites are based on oxidative stress, parasites may rely on their antioxidant systems to preclude immune defenses. Therefore, understanding of the effect of oxidative stress on vital characteristics of Acanthamoeba castellanii (T4 genotype) and the antioxidant defense responses of Acanthamoeba to oxidative status will cast light on immune cell-parasite interactions. Acanthamoeba T4 cells were cultured in RPMI-1640 medium containing different concentrations of hydrogen peroxide (H2O2). The survival of Acanthamoeba was evaluated by MTT assay and the IC50 concentration was calculated. The total antioxidant capacity (TAC) of the parasite was determined by the cupric reducing antioxidant capacity (CUPRAC) method. Malondialdehyde (MDA) as a marker of lipid peroxidation, protein carbonyl content as a measure of oxidized protein, total thiol (-SH) groups present on proteins as a major source of cellular antioxidants, and total oxidant status (TOS) were evaluated by colorimetric methods. The reactive oxygen species level increased markedly after induction of oxidative stress by the treatment of Acanthamoeba T4 with H2O2. Exposure to H2O2 also significantly increased the MDA and protein carbonyl content. The TOS level and total thiol groups also increased in the treated group compared to those in untreated parasites, although the results were not statistically significant. The TAC level was found to be significantly higher in H2O2-treated parasites, confirming that the parasite fosters its total antioxidant capacity to overcome oxidative conditions. This study showed that under oxidative stress, the defense reactions of the parasite are in part mediated by increasing its antioxidant activity, which is important for the survival of the parasite.

First Synthetic Study of Cube-Like Cobalt Hydroxystannate Nanoparticles as Photocatalyst for Drimarene Red K-4BL Degradation and Fuel Additive

This research article describes the development of a simple and sensitive approach with less runtime for the estimation of photo degradation of an anthraquinone dye drimarene red K-4BL in the presence of newly synthesized nano catalyst. Hydrothermal approach is used to synthesize cobalt hydroxystannate by using precursor salts of chloride i.e. stannic chloride, cobalt chloride and sodium hydroxide is used as a precipitating agent. Various techniques were used to analyze the product. Two major applications of synthesized nanocubes are investigating the efficiency of modified fuel and as a photocatalyst for dye degradation. Anthraquinone dye (drimarene red K-4BL) is degraded by the newly synthesized nanoparticles which is used as a catalyst in aqueous medium. In the presence of sun irradiation at different concentrations of hydrogen peroxide and catalyst, kinetics of photo catalytic degradation of dye is monitored on ultra violet visible spectrophotometer. Efficiency of modified fuel is analyzed by studying the various parameters such as flash point, fire point, pour point and cloud point, etc. at different dosage of Cobalt hydroxystannate. By changing the dosage of the catalyst, values of these parameters changed significantly.

Evaluation of the fusion inhibitor P3 peptide as a potential microbicide to prevent HIV transmission in women.

Microbicides are an important strategy for preventing the sexual transmission of HIV but, so far, the most advanced tenofovir-based microbicides have had modest efficacy. This has been related to adherence problems and high prevalence of tenofovir-resistant HIV-1 strains. P3 is a new peptide with potent activity against HIV that may be a good microbicide candidate. In this work P3 was formulated in a gel of hydroxyethyl cellulose and its activity, stability and safety profile in Balb/c mice were evaluated. HIV infection was fully blocked by a 1.5% gel containing P3 at the IC90 (366.4 nM) concentration. The antiviral activity did not change at 4°C during 4 months and at 25, 37 and 65°C for 1 week. P3 was stable and fully functional at acidic pH up to 24h, under different concentrations of hydrogen peroxide and in the presence of genital fluids up to 48h. P3 had no antibacterial activity and did not affect sperm motility and vitality. Finally, P3 didn’t cause significant alterations in the vaginal epithelium of Balb/c mice at 0.06 (456.8 μM) and 0.2 mg/day (1522.7 μM) doses. These findings indicate that P3 is an excellent candidate for further development as a microbicide gel for the prevention of HIV transmission in women.

Degradation product characterization of therapeutic oligonucleotides using liquid chromatography mass spectrometry.

Synthetic antisense phosphorothioate oligonucleotides (PS) have undergone rapid development as novel therapeutic agents. The increasing significance of this class of drugs requires significant investment in the development of quality control methods. The determination of the many degradation pathways of such complex molecules presents a significant challenge. However, an understanding of the potential impurities that may arise is necessary to continue to advance these powerful new therapeutics. In this study, four different antisense oligonucleotides representing several generations of oligonucleotide therapeutic agents were evaluated under various stress conditions (pH, thermal, and oxidative stress) using ion-pairing reversed-phase liquid chromatography tandem mass spectrometry (IP-RPLC-MS/MS) to provide in-depth characterization and identification of the degradation products. The oligonucleotide samples were stressed under different pH values at 45 and 90°C. The main degradation products were observed to be losses of nucleotide moieties from the 3'- and 5'-terminus, depurination, formation of terminal phosphorothioates, and production of ribose, ribophosphorothioates (Rp), and phosphoribophosphorothioates (pRp). Moreover, the effects of different concentrations of hydrogen peroxide were studied resulting in primarily extensive desulfurization and subsequent oxidation of the phosphorothioate linkage to produce the corresponding phosphodiester. The reaction kinetics for the degradation of the oligonucleotides under the different stress conditions were studied and were found to follow pseudo-first-order kinetics. Differences in rates exist even for oligonucleotides of similar length but consisting of different sequences. Graphical abstract Identification of degradation products across several generations of oligonucleotide therapeutics using LC-MS.

English

Cat thyme is an important medicinal plant used for treating many diseases. With renewed interest as arthropod deterrent and repellents, there is immediate need to cultivate cat thyme on large scale in the laboratory. To improve cat thyme seed germination, obstacles involved in its seed dormancy must be investigated. To address such challenges, mechanical abrasion and chemical treatments were used to enhance the rate of seed germination. The application of mechanical abrasion with low speed grinding using walnut husk to improve the germination of cat thyme seeds was studied. In addition, to improve the seed germination percentage, the seeds were further treated with different concentrations of hydrogen peroxide (2.5, 5, 10 and 15%). The results show that the treatment of 5% hydrogen peroxide concentration promoted the seed germination rate. After the aforementioned different treatments, Baggy method was used and it achieved 50% germination rate within 30 days. In conclusion, the germination tests showed that cat thyme seed germination improved with combination of mechanical abrasion and 5% hydrogen peroxide treatments. Key words: Cat thyme, seed germination percentage, hydrogen peroxide.

Structure dependent luminescence, peroxidase mimetic and hydrogen peroxide sensing of samarium doped cerium phosphate nanorods.

Rare earth phosphates have been used extensively in luminescent phosphors, bio-imaging, catalysis, and sensors. However, there is a need to correlate the structural-chemical changes associated with stability and performance. In the present work, hydrothermally synthesized CePO4:Smx (x = 0, 5 and 10 mol%) nanorods were annealed at different temperatures to understand the modulations in structure as well as optical and enzyme mimetic properties. As prepared samarium doped cerium phosphate (SCP) nanorods crystallized in a hydrated hexagonal structure transformed into an anhydrous hexagonal and a monoclinic structure on annealing at 400 °C and 800 °C, respectively. Though temperature did not affect the rod-like morphology of the SCP, the lattice strain changed from compressive to tensile. Monoclinic SCP exhibited excellent emission until 5% Sm3+ doping while the quenching effect dominated at 10% Sm3+. Monoclinic SCP samples demonstrated higher peroxidase-like enzymatic activity in comparison to natural enzyme HRP and hexagonal SCP. A mechanism for the enhanced peroxidase-like activity of the monoclinic structure was proposed based on the fluorescence property of terephthalic acid and the surface peroxo complex using Raman spectroscopy. Fluorimetric detection based on the luminescent quenching effect of the monoclinic SCP nanorods treated with different concentrations of hydrogen peroxide showed a linear response from 0 to150 μM concentration with a detection limit (LOD) of 3.17 μM H2O2. Our results demonstrate the importance of structure for enzyme mimetic activity.

Evaluation of different methods for efficient extraction of hemicelluloses leaves and tops of sugarcane

En Colombia se producen alrededor de 9 millones de toneladas de residuos de la cosecha de la caña de azúcar por hectárea cada año, que no han sido valorizados hacia ningún tipo de producto. Es necesario conocer su composición, en especial el contenido de hemicelulosas, para dilucidar el proceso para obtener los monosacáridos de éstas y aislarlos eficientemente. Para separar las hemicelulosas puras, se estudiaron cinco procesos de extracción a partir de las hojas y cogollos de las variedades de caña de azúcar CC 8592, CC 8475 y V 7151. Después de evaluar la eliminación de ceras con etanol y mezclas de cloroformo-metanol, los residuos se expusieron a diferentes concentraciones de peróxido de hidrógeno y clorito de sodio acidificado para lograr su deslignificación. Adicionalmente, se desarrollaron procedimientos de extracción con hidróxido de sodio e hidróxido de potasio, y de precipitación. El método que logró el mayor rendimiento fue el de desceración con metanol-cloroformo y deslignificación con clorito de sodio y borohidruro de sodio, con un rango de recuperación entre 0.20-0.34 g hemicelulosas /g residuo seco en las variedades estudiadas.

Effect of steam-pretreatment combined with hydrogen peroxide on lignocellulosic agricultural wastes for bioethanol production: Analysis of derived sugars and other by-products

The hydrogen peroxide, a green impregnating agent suitable for lignocellulosic biomass to bioethanol process, was used to pretreat sugarcane bagasse by steam explosion. Two different concentrations of hydrogen peroxide (0.2% and 1%) were investigated. Then, the biomass was hydrolyzed after pretreatment using cellulase. The amount released of: (i) cellobiose; (ii) monosaccharides, as glucose, xylose, arabinose and mannose and (iii) lignocellulose derived by-products, as furans and small organic acids (acetic, formic, and levulinic acid), was evaluated in the hydrolysate samples, previously pretreated both in the presence and absence of impregnating agent. By adding of hydrogen peroxide in steam-pretreatment, the average yield increase was 12% for glucose and as high as 34% for xylose, and cellobiose yield was decreased of about 30%. No significant increase has been observed in arabinose and mannose yield. Furthermore, the hydrogen peroxide seems not increased the formation of lignocellulose derived by-products during pretreatment process, with the exception of the levulinic acid.

Reactive oxygen species induce injury of the intestinal epithelium during hyperoxia.

Long-term therapeutic hyperoxia may exert serious toxic effects on intestinal epithelial cells in vitro and in vivo. The aim of the present study was to investigate the cause of this intestinal injury under conditions of hyperoxia. Caco-2 cells were treated with different concentrations of hydrogen peroxide (H2O2) and 85% hyperoxia for 24 h. Higher rates of injury of Caco-2 cells were observed in the hyperoxia and H2O2 groups compared with the control group. The reactive oxygen species (ROS) level of the hyperoxia group was significantly higher compared with that of the 400 μM H2O2 group. The protein and gene levels of RelA, RelB, hypoxia-inducible factor-1α, tumor necrosis factor-α and apoptosis signal-regulating kinase 1 were significantly higher in the hyperoxia and H2O2 groups compared with those in the control group. In conclusion, during hyperoxia, intestinal epithelial cells were destroyed and the levels of ROS were increased. Therefore, ROS may play an important role in intestinal injury in a hyperoxic environment.

Morphologically Controlled Synthesis of Cubes like Tin Oxide Nanoparticles and Study of its Application as Photocatalyst for Congo Red Degradation and as Fuel Additive

Tin oxide nanocubes are synthesized by hydrothermal approach by using the stannic chloride as precursor salt and sodium hydroxide as precipitating agent in aqueous media. Synthesized product is analyzed by various techniques: X-ray powder diffraction analysis (XRD) and scanning electron microscopy (SEM). Structural composition and parameters of the product are analyzed by (XRD). Morphology of the product is analyzed by (SEM). These synthesized nanocubes are used in two applications: (1) as a photocatalyst and (2) as a fuel additive. Synthesized nanoparticles are used as photocatalyst for the degradation of an organic dye (Congo red) in aqueous medium. Photocatalytic degradation kinetics of dye is monitored at different concentrations of hydrogen peroxide and catalyst in the presence of sunlight. The percentage conversion of dye is also calculated for different concentrations of hydrogen peroxide and catalyst. Efficiency of fuel is analyzed by studying various parameters: flash point, fire point, cloud point, pour point, kinematic viscosity, specific gravity and calorific value at different dosage of SnO2 (10, 20, 30 and 40 ppm). It is found that values of these parameters changes significantly by changing the dosage of catalyst.

Effect of vital bleaching with solutions containing different concentrations of hydrogen peroxide and pineapple extract as an additive on human enamel using reflectance spectrophotometer: An in vitro study

Aim:This study aims to evaluate the color change in human enamel bleached with three different concentrations of hydrogen peroxide, containing pineapple extract as an additive in two different timings, using reflectance spectrophotometer.Background:The study aimed to investigate the bleaching efficacy on natural teeth using natural enzymes.Materials and Methods:Baseline color values of 10 randomly selected artificially stained incisors were obtained. The specimens were divided into three groups of 20 teeth each: Group 1 – 30% hydrogen peroxide, Group II – 20% hydrogen peroxide, and Group III – 10% hydrogen peroxide. One half of the tooth was bleached with hydrogen peroxide, and other was bleached with hydrogen peroxide and pineapple extract for 20 min (Subgroup A) and 10 min (Subgroup B).Statistical Analysis:The results were statistically analyzed using student's t-test.Results:The mean ΔE values of Group IA (31.62 ± 0.9), Group IIA (29.85 ± 1.2), and Group IIIA (28.65 ± 1.2) showed statistically significant higher values when compared to the mean Δ E values of Group 1A (25.02 ± 1.2), Group IIA (22.86 ± 1.1), and Group IIIA (16.56 ± 1.1). Identical results were obtained in Subgroup B.Conclusion:The addition of pineapple extract to hydrogen peroxide resulted in effective bleaching.

Protection of Human Umbilical Vein Endothelial Cells against Oxidative Stress by MicroRNA-210.

Oxidative stress induces endothelial cell apoptosis and promotes atherosclerosis development. MicroRNA-210 (miR-210) is linked with apoptosis in different cell types. This study aimed to investigate the role of miR-210 in human umbilical vein endothelial cells (HUVECs) under oxidative stress and to determine the underlying mechanism. HUVECs were treated with different concentrations of hydrogen peroxide (H2O2), and cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and ATP assay. To evaluate the role of miR-210 in H2O2-mediated apoptosis, gain-and-loss-of-function approaches were used, and the effects on apoptosis and reactive oxygen species (ROS) level were assayed using flow cytometry. Moreover, miR-210 expression was detected by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), and expression of the following apoptosis-related genes was assessed by qRT-PCR and Western blot at the RNA and protein level, respectively: caspase-8-associated protein 2 (CASP8AP2), caspase-8, and caspase-3. The results showed that H2O2 induced apoptosis in HUVECs in a dose-dependent manner and increased miR-210 expression. Overexpression of miR-210 inhibited apoptosis and reduced ROS level in HUVECs treated with H2O2. Furthermore, miR-210 downregulated CASP8AP2 and related downstream caspases at protein level. Thus, under oxidative stress, miR-210 has a prosurvival and antiapoptotic effect on HUVECs by reducing ROS generation and downregulating the CASP8AP2 pathway.

Excess mechanical stress and hydrogen peroxide remodel extracellular matrix of cultured human uterosacral ligament fibroblasts by disturbing the balance of MMPs/TIMPs via the regulation of TGF‑β1 signaling pathway.

The regulation of the extracellular matrix (ECM) by mechanical stress is of interest as the ECM is essential in the development of pelvic organ prolapse. In the present study, the effect of overexposure to mechanical stress on the ECM, and the probable underlying mechanisms in cultured human uterosacral ligament fibroblasts (hUSLFs), was explored. Mechanical stress has an effect on oxidation‑antioxidation products in parametrial ligament fibroblasts. Thus, hUSLFs were incubated with different concentrations of hydrogen peroxide to elucidate any potential interactions. Excess mechanical stress and H2O2 inhibited cell proliferation, and decreased mRNA and protein expression levels of ECM components, collagen 1, collagen 3 and elastin. Further analysis revealed that the mRNA expression level of matrix metalloproteinase‑2 (MMP‑2) was increased and TIMP metallopeptidase inhibitor2 (TIMP‑2) decreased, and in addition the MMP2/TIMP2 mRNA ratio was increased, which may facilitate the degradation of the ECM. Due to the key role of the transforming growth factor β1 (TGF‑β1)/mothers against decapentaplegic homolog 2 (Smad2) signaling pathway in fibrosis, the present study investigated the effect of excess mechanical stress and H2O2 on TGF‑β1/Smad2 signaling. The results indicated that excess mechanical stress and H2O2 treatment suppressed phosphorylated Smad2 expression and decreased the levels of TGF‑β1. Activation of the TGF‑β1 signaling pathway by either mechanical stress or H2O2 was demonstrated to attenuate cell proliferation and ECM components, and also increased the MMP2/TIMP2 mRNA ratio. These findings suggested that mechanical stress and H2O2 overexposure inhibit cell proliferation and remodel the ECM network via regulation of the TGF‑β1 signaling pathway.

Reaction pathways during oxidation of cereal β-glucans

Oxidation of cereal β-glucans may affect their stability in food products. Generally, polysaccharides oxidise via different pathways leading to chain cleavage or formation of oxidised groups within the polymer chain. In this study, oxidation pathways of oat and barley β-glucans were assessed with different concentrations of hydrogen peroxide (H2O2) or ascorbic acid (Asc) with ferrous iron (Fe2+) as a catalyst. Degradation of β-glucans was evaluated using high performance size exclusion chromatography and formation of carbonyl groups using carbazole-9-carbonyloxyamine labelling. Furthermore, oxidative degradation of glucosyl residues was studied. Based on the results, the oxidation with Asc mainly resulted in glycosidic bond cleavage. With H2O2, both glycosidic bond cleavage and formation of carbonyl groups within the β-glucan chain was found. Moreover, H2O2 oxidation led to production of formic acid, which was proposed to result from Ruff degradation where oxidised glucose (gluconic acid) is decarboxylated to form arabinose.

Oxidative Stress Induces Senescence in Cultured RPE Cells.

The aim of this research is to determine whether oxidative stress induces cellular senescence in human retinal pigment epithelial cells. Cultured ARPE19 cells were subjected to different concentrations of hydrogen peroxide to induce oxidative stress. Cells were seeded into 24-well plates with hydrogen peroxide added to cell medium and incubated at 37°C + 5% CO2 for a 90-minute period [at 0, 300, 400 and 800 micromolar (MCM) hydrogen peroxide]. The number of viable ARPE19 cells were recorded using the Trypan Blue Dye Exclusion Method and cell senescence was measured by positive staining for senescence-associated beta-galactosidase (SA-beta-Gal) protein. Without hydrogen peroxide treatment, the number of viable ARPE19 cells increased significantly from 50,000 cells/well to 197,000 within 72 hours. Treatment with hydrogen peroxide reduced this level of cell proliferation significantly (to 52,167 cells at 400 MCM; to 49,263 cells at 800 MCM). Meanwhile, cells with a high level of positive senescence-indicator SA-Beta-Gal-positive staining was induced by hydrogen peroxide treatment (from a baseline level of 12% to 80% at 400 MCM and at 800 MCM). Our data suggests that oxidative stress from hydrogen peroxide treatment inhibited ARPE19 cell proliferation and induced cellular senescence.

Evaluating different concentrations of hydrogen peroxide in an automated room disinfection system.

A comparative study was made on the efficacy of 5, 10 and 35% weight by weight (w/w) hydrogen peroxide solutions when applied using an automated room disinfection system. Six-log biological indicators of methicillin-resistant Staphylococcus aureus (MRSA) and Geobacillus stearothermophilus were produced on stainless steel coupons and placed within a large, sealed, environmentally controlled enclosure. Five percent hydrogen peroxide was distributed throughout the enclosure using a Bioquell hydrogen peroxide vapour generator (BQ-50) for 40min and left to reside for a further 200min. Biological indicators were removed at 10-min intervals throughout the first 120min of the process. The experiment was repeated for 10 and 35% hydrogen peroxide solutions. Five percent and 10% hydrogen peroxide solutions failed to achieve any reduction of MRSA, but achieved full kill of G.stearothermophilus spores at 70 and 40min respectively. Thirty-five percent hydrogen peroxide achieved a 6-log reduction of MRSA after 30min and full kill of G.stearothermophilus at 20min. The concentration of 5% hydrogen peroxide within the enclosure after the 200-min dwell was measured at 9·0ppm. This level exceeds the 15-min Short Term Exposure Limit (STEL) for hydrogen peroxide of 2·0ppm. Users of automated hydrogen peroxide disinfection systems should review system efficacy and room re-entry protocols in light of these results. This research allows hospital infection control teams to consider the impact and risks of using low concentrations of hydrogen peroxide for disinfection within their facilities, and to question automated room disinfection system providers on the efficacy claims they make. The evidence that low concentration hydrogen peroxide solutions do not rapidly, autonomously break down, is in contradiction to the claims made by some hydrogen peroxide equipment providers and raises serious health and safety concerns. Facilities using hydrogen peroxide systems that claim autonomous break down of hydrogen peroxide should introduce monitoring procedures to ensure rooms are safe for re-entry and patient occupation.